(i) Technical Field
The present invention relates to focal plane shutters and optical apparatuses provided with the same.
(ii) Related Art
In an optical apparatus electrically storing captured images, it is proposed that an image pickup element is used as a conventional finder. In this case, the image pickup element has to capture an object before taking a picture. A focal plane shutter used for such an optical apparatus has to keep an opening opened. Also, the image pickup element has to continuously capture an object during movie shooting. In this case, the focal plane shutter also has to keep the opening opened.
Japanese Unexamined Patent Application Publication No. 56-109323 discloses a focal plane shutter equipped with: a leading blade and a trailing blade opening and closing an opening formed in a board; actuators driving the leading blade and the trailing blade, and assist springs biasing the leading blade and the trailing blade in respective moving directions.
In such a case where the image pickup element is used as the conventional finder, the leading blade and the trailing blade are positioned away from the opening to keep the opening opened before taking a picture or during movie shooting. In such a case, when the impact is applied to the optical apparatus, the leading blade or the trailing blade might move toward the opening. In particularly, in a case where the trailing blade is biased in the moving direction as disclosed in Japanese Unexamined Patent Application Publication No. 56-109323, such a problem might arise.